A communication device that performs bidirectional multiplex communication between a plurality of slave communication devices and the communication device is provided with: a first port connected to one end section of a transmission line to which the slave communication devices are connected; a second port connected to the other end section of the transmission line; and a current detection unit connected to the first port and the second port. An operation voltage is supplied from the communication device to the slave communication devices, a change of the quantity of a current flowing in the first port and/or the second port is detected by means of the current detection unit, and on the basis of the current quantity change, occurrence of disconnection in the transmission line is detected.
Legal claims defining the scope of protection, as filed with the USPTO.
1. A communication device for making bidirectional multiplex communication with a plurality of slave communication devices, comprising: a first port connected to one end of a transmission line to which the slave communication devices are connected; a second port connected to the other end of the transmission line; and a current detection unit connected to the first port and the second port, wherein an operation voltage is supplied from the communication device to the slave communication devices via the transmission line, and the current detection unit detects a change in the quantity of current flowing in at least one of the first port and the second port, and detects an occurrence of disconnection on the transmission line on the basis of the change in the quantity of current, wherein, when transferring data to the slave communication devices, the communication device changes a voltage of the transmission line depending on the data to be transmitted, wherein when transmitting data to the communication device, each of the slave communication devices changes the quantity of current in the transmission line depending on the data to be transmitted at a mutually-different timing, the communication device comprises a table indicating a correspondence between each of the slave communication devices and a physical position on the transmission line to which each of the slave communication devices is connected, when receiving data from each of the slave communication devices, the communication device registers a current width of the quantity of current detected by the current detection unit in the table in association with the slave communication device from which the data is received, and the communication device specifies a disconnected place on the transmission line on the basis of a change between the current widths corresponding to the slave communication devices registered in the table.
2. The communication device according to claim 1 , wherein when the quantity of current flowing in the first port is different from the quantity of current flowing in the second port, an occurrence of disconnection on the transmission line is detected.
3. The communication device according to claim 1 , wherein the table comprises identification information for specifying a slave communication device, and the communication device generates the identification information on the basis of a data reception timing.
4. The communication device according to claim 1 , wherein the table comprises identification information for specifying a slave communication device, and identification information is included in data from a slave communication device.
5. The communication device according to claim 1 , wherein the transmission line comprises a positive line and a negative line, each of the first port and the second port comprises a port connected to the positive line and a port connected to the negative line, and the current detection unit detects the quantity of current flowing in the port connected to the positive line and the quantity of current flowing in the port connected to the negative line.
6. A communication system comprising: a first transmission line with a pair of ends; a plurality of slave communication devices connected to the first transmission line and operating by a voltage from the first transmission line; and a master communication device comprising a first port connected to one end of the first transmission line, a second port connected to the other end of the first transmission line, and a current detection unit connected to the first port and the second port, and directed for making bidirectional multiplex communication with the slave communication devices, wherein the current detection unit detects disconnection on the first transmission line on the basis of a change in the quantity of current flowing in at least one of the first port and the second port, wherein, when transferring data to the slave communication devices, the master communication device changes a voltage of the first transmission line depending on the data to be transmitted, wherein when transmitting data to the master communication device, each of the slave communication devices changes the quantity of current in the first transmission line depending on the data to be transmitted at a mutually-different timing, the master communication device comprises a table indicating a correspondence between each of the slave communication devices and a physical position on the first transmission line to which each of the slave communication devices is connected, when receiving data from each of the slave communication devices, the master communication device registers a current width of the quantity of current detected by the current detection unit in the table in association with the slave communication device from which the data is received, and the master communication device specifies a disconnected place on the first transmission line on the basis of a change between the current widths corresponding to the slave communication devices registered in the table.
7. The communication system according to claim 6 , wherein when the quantity of current flowing in the first port is different from the quantity of current flowing in the second port, an occurrence of disconnection on the first transmission line is detected.
8. The communication system according to claim 6 , wherein the first transmission line comprises a positive line and a negative line, each of the first port and the second port comprises a port connected to the positive line and a port connected to the negative line, and the current detection unit detects the quantity of current flowing in the port connected to the positive line and the quantity of current flowing in the port connected to the negative line.
9. The communication system according to claim 6 , comprising: a second transmission line connected to the first port at one end and connected to the second port at the other end; and a plurality of slave communication devices connected to the second transmission line.
10. The communication system according to claim 6 , wherein the master communication device comprises a third port connected to the current detection unit, and the communication system comprises: a third transmission line connected to the second port at one end and connected to the third port at the other end; and a plurality of slave communication devices connected to the third transmission line.
11. A communication system comprising: a transmission line with a pair of ends; a plurality of slave communication devices connected to the transmission line; and a master communication device having a first port connected to one end of the transmission line and a second port connected to the other end of the transmission line and directed for making bidirectional multiplex communication with the slave communication devices, wherein when transmitting data to the master communication device, each of the slave communication devices changes the quantity of current in the transmission line depending on the data to be transmitted at a mutually-different timing, the master communication device comprises: a current detection unit for detecting the quantity of current flowing in at least one of the first port and the second port; and a table indicating a correspondence between each of the slave communication devices and a physical position on the transmission line to which each of the slave communication devices is connected, and when receiving data from each of the slave communication devices, the master communication device registers a current width of the quantity of current detected by the current detection unit in the table in association with the slave communication device from which the data is received, and specifies a disconnected place on the transmission line on the basis of a change between the current widths corresponding to the slave communication devices registered in the table.
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March 24, 2016
March 3, 2020
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